Possible causes of uneven skin tone on a sixteen year old girl’s face are caused by genetic factors, environmental factors such as ultraviolet rays, and can also be caused by skin disorders such as acne and pityriasis alba. If a girl has uneven skin color on her face, it can be caused by hereditary factors and is usually of no concern. In addition, if there is a lot of outdoor activity, there can be a darkening of the sun-drenched areas of the face and uneven skin tone. If acne is present, it is easy to leave red and black acne marks on the skin due to inflammation. In the presence of pityriasis alba, there may be round lesions on the face, which may appear red or pale in color and are covered with white, bran-like scales. If uneven skin color is evident on the face, visit a hospital to identify it and treat it accordingly.